Emerson EZH, EZHSO Instruction Manual

Instruction Manual

NTAEZH0811

November 2008 - Rev. 06

Types EZH and EZHSO

Types EZH and EZHSO Pressure Reducing Regulators

Contents
Introduction ........................................................................	2
Characteristics ...................................................................	3
Labelling ............................................................................	5
Dimensions and Weights ...................................................	6
Description .........................................................................	8
Principle of Operation.........................................................	8
Monitoring Systems............................................................	11
Installation .........................................................................	13
Startup and Adjustment .....................................................	15
Shutdown ...........................................................................	16
Maintenance ......................................................................	17
Troubleshooting .................................................................	24
Spare Parts ........................................................................	25
Parts List ............................................................................	26

!WARNING

Failure to follow these instructions or to properly install and maintain this equipment could result in an explosion and/or fire causing property damage and personal injury or death.

Fisher® regulators must be installed, operated, and maintained in accordance with federal, state, and local codes, rules and regulations, and Emerson Process Management Regulator Technologies, Inc. (Regulator Technologies) instructions.

If the regulator vents gas or a leak develops in the system, service to the unit may be required. Failure to correct trouble could result in a hazardous condition.

Call a gas service person to service the unit. Only a qualified person must install or service the regulator.

R94

Figure 1. Type EZH Pressure Reducing Regulator

TYPE PRX-120

TYPE PRX-120/AP

Figure 2. PRX Series Pressure Reducing Pilots

Types EZH, EZHSO, EZH OS2, and EZHSO OS2 regulators are in conformity with the

Pressure Equipment Directive

PED 97/23/EC and are classified in Category IV.

Europe, Middle East, and Africa Document Only

www.fisherregulators.com

Types EZH and EZHSO

INTRODUCTION

Scope of Manual

This manual provides installation, startup, maintenance, and parts ordering information for the Types EZH and EZHSO pressure-reducing regulators and Type PRX pilot with Type SA/2 pilot supply filter regulator.

Information on other equipment used with this regulator is found in separate manuals.

Product Description

Types EZH and EZHSO regulators are accurate pilotoperated pressure balanced, soft-seated regulators. They are designed for use in high pressure natural gas transmission/city gate stations, large capacity distribution systems, and power plant feeds. They provide smooth, reliable operation, tight shutoff, and long life.

Type EZHSO "Spring-to-Open" version could be used when other overpressure protection options are foreseen, for example in a monitor configuration. In this case, in event of failure, the main regulator will stay completely open, allowing the monitor to take control. The monitor could be "Spring-to-Close" to ensure a double protection to downstream pipe.

Available Configurations:

•Types EZH and EZHSO ("E Body")

Single regulator without slam shut

•Types EZH and EZHSO ("X Body")

Single regulator in a X Body

In case of modification made on a pressure equipment like cap replacement by a slam shut it's mandatory to comply to the local codes, rules and regulations. Contact us imperatively.

•Types EZH OS2 and EZHSO OS2 ("X Body")

Single regulator with integrated slam shut

Pilot Description

Type PRX Pilot

The Types EZH and EZHSO pressure-reducing regulators can be equipped with a PRX Series pilot mounted on the main valve for pressure reducing or wide-open monitoring applications. The PRX Series pressure reducing pilots have the ability to handle a wide range of setpoints from 1 to 80 bar:

•Type PRX/120:

Outlet pressure range of 1 to 40 bar. The Type PRX/120 can be used as the pilot on single stage pressure reducing regulators, as the monitor pilot, or as the working pilot in wide-open monitor systems.

•Type PRX/120-AP:

Outlet pressure range of 30 to 80 bar. The Type PRX/120-AP can be used as the pilot on single stage pressure reducing regulators, as the monitor pilot, or as the working pilot in wide-open monitor systems.

•Type PRX/125:

Identical to the Type PRX/120, except the restriction screw is removed. The Type PRX/125 can only be used as the monitor override pilot on working monitor applications.

•Type PRX/125-AP:

Identical to the Type PRX/120-AP, except the restriction screw is removed. The Type PRX/125-AP can only

be used as the monitor override pilot on working monitor applications.

•Type SA/2 Pilot Supply Filter Regulator:

The Type SA/2 pilot supply filter regulator provides a constant pressure supply to the PRX Series pilot of 3 bar over the set pressure. The Type SA/2 has an integral

5-micron filter. For easy maintenance a block valve can be installed to separate the regulator from the pilot.

Regulator Options

•Silencer (Figure 22)

The Type EZH silencer (Whisper III) is integrated in the regulator and is composed of a drilled cage.

The Whisper III silencer is available for DN 25, 50, 80, and 100 and allows a noise attenuation up to 8dB.

•Flow Coefficient Reduction (Figure 16)

The flow reduction is realised by replacement of the regulator standard seat by a reduction seat ( key 2).

•Type RPE Electrical Pilot Heater (Figure 25)

The Type RPE is used for reheating the gas supplying pressure reducing regulator pilots. The Type RPE avoids the inconveniences caused by freezing which can occur during high pressure drops.

Actuator

The actuator is an integral pressure type. All pressure parts are designed to resist up to 100 bar. The diaphragm is strong and can resist to a differential of 100 bar.

Europe, Middle East, and Africa Document Only

2

Types EZH and EZHSO

CHARACTERISTICS

Table 1. General Characteristics for Types EZH and EZHSO Regulator

OPERATING PRESSURE
	A352LCC Body, Actuator, Valve,			PS	100 bar max
	Pilot Body, Slam shut
	Associated BMS(1), according to size			PSD	10 to 100 bar
	Type			IS	Integral strength(4)
OPERATING TEMPERATURE(2)				TS	-20 / 60°C Class 2
Sizes available				DN	25, 50, 80, and 100
Noise level reduction				Up to 8 dB
REGULATOR
European EN Standard					EN 334
Inlet Pressure				Pu	2 to 100 bar
Outlet Pressure				Pd	1 to 80 bar
Minimum Differential				DP min	1 bar (Type EZH)
					3.8 bar (Type EZHSO)
Maximum Differential				DP max	99 bar (Type EZH)
					96.2 bar (Type EZHSO)
Accuracy (optimal)				AC	See Table 2
Lock-Up Pressure Class				SG	Up to 5%(3)
Lock-Up Pressure Zone Class				SZ	Up to 5%(3)
(1)	BMS - Safety Manometric Box	(3)		Contact us with your operating conditions
(2)	Standard version	(4)		Depending on BMS configuration for Type EZH OS2

SLAM SHUT

European EN Standard					EN 14382
Operation Class					A or B (see Figure 3)
Maximum Operating Differential			DP max		100 bar
Response Time			ta		<1 s
		Diaphragm,			Up to ±2.5%
Accuracy		Bellows	AG
		Piston			Up to ±5%
Set Pressure Range			Wdu-Wdo		0.010 / 100 bar
Flow Coefficient			Qf		13
Internal Automatic Bypass			Cg		25
Rearming		Manual after rectification of fault
Position Indicator		On mechanism box
			Fluid

Groups 1 and 2 according to PED 97/23/EC, Gas 1st and 2nd family according to EN 437, or other gases (compressed air, nitrogen).

The gas must be non corrosive, clean

(filtration on inlet side necessary) and dry.

Table 2. Outlet Pressure Ranges, Accuracy Class, and Pilot Spring Information

	TYPE	OUTLET PRESSURE	AC (ACCURACY CLASS)		PILOT CONTROL SPRING INFORMATION
		ADJUSTMENT RANGES (bar)	TYPE EZH	TYPE EZHSO	Spring Colour
		1.0 to 1.8	2.5%	2.5%	Yellow
		1.8 to 3.0	2.5%	2.5%	Green
		3.0 to 5.5	2.5%	2.5%	Blue
	PRX/120 and	5.5 to 8.5	2.5%	2.5%	Black
	PRX/125	8.5 to 14.5	1%	2.5%	Silver
		14.5 to 23.0	1%	2.5%	Gold
		23.0 to 30.0	1%	2.5%	Aluminium
		30.0 to 40.0	1%	2.5%	Red
	PRX/120-AP and	30.0 to 80.0	1%	2.5%	Clear
	PRX/125-AP
					R95

		Table 3a. 2:1 Line Flow Coefficients, Regulator, and Slam-Shut Travel
				TYPES EZH (DN 25 - 100) AND EZHSO (DN 25 - 100)
	REDUCTION			WITH SLAM SHUT (X BODY)				WITHOUT SLAM SHUT (E BODY)
		DN 25		DN 50	DN 80	DN 100	DN 25		DN 50	DN 80		DN 100
	0	284		1078	2247	3567	280		1088	2266		3696
Qf	1	210		908	1684	2969	218		829	1698		2902
	2	126		671	1058	1763	128		607	1066		1784
	3	79		385	685	1062	81		370	690		1072
	0	550		2092	4359	6920	544		2110	4396		7170
Cg	1	408		1762	3266	5760	423		1609	3294		5630
	2	245		1301	2052	3420	249		1177	2069		3460
	3	154		746	1328	2060	157		718	1339		2080
	0	31.3		38.3	30.8	32.5	35.5		33.5	30.8		31.4
C1	1	34.3		35.3	33.9	35.3	38.7		31.9	33.9		34.2
	2	33.6		38.8	37.8	37.3	39.7		35.6	37.8		36.3
	3	32.1		40.8	33.6	37.1	39.1		38.2	33.6		37.3
Regulator travel (mm)		9		17	25	30	9		17	25		30
Slam-shut travel (mm)			15		30	50

R96

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Types EZH and EZHSO

Table 3b. 2:1 Line Flow Coefficients, Regulator with Integrated Whisper III Silencer

TYPES EZH (DN 25 - 100) WITH WHISPER III AND EZHSO (DN 25 - 100) WITH WHISPER III

	REDUCTION		SLAM SHUT INTEGRATED (X BODY)						WITHOUT SLAM SHUT (E BODY)
		DN 25		DN 50	DN 80		DN 100	DN 25		DN 50	DN 80		DN 100
	0	223		781	1693		2742	255		793	1708		2789
Qf	1	215		764	1418		2479	209		716	1172		2438
	2	140		603	975		1644	127		566	984		1711
	3	87		370	685		1041	81		358	690		1057
	0	433		1516	3285		5320	495		1539	3313		5410
Cg	1	417		1482	2751		4810	406		1389	2774		4730
	2	273		1169	1892		3190	247		1099	1908		3320
	3	168		718	1328		2020	158		695	1339		2050
	0	35.5		37	30.8		31.7	33.8		33.5	30.8		30.4
C1	1	35.4		37.5	33.6		34.1	39.4		34.1	33.6		32.4
	2	32.3		39.5	37.1		36.4	39.9		35.7	37.1		35.7
	3	32.9		39.4	38.3		37.6	39.9		37.7	38.3		37.3

Table 4. Failure Mode Analysis

	PART NAME	FAILURE	CAUSE OF	EFFECT	REGULATOR TYPE	REGULATOR REACTION MODE
		(WORST CASE)	FAILURE
				Decrease of feeding	EZHSO	Open	---
		Filter blocked/	Debris or aromatics	pressure gives
	Filter
		clogged	present in the gas	decrease of	EZH	---	Close
				motorization pressure
			Debris or aromatics	Increase	EZHSO	Open	---
	Pilot Disk	Pilot cannot be closed		motorization
			present in the gas		EZH	Open	---
				pressure
	Pilot Lower		Debris or aromatics	Decrease	EZHSO	Open	---
		Pilot cannot control		motorization
	Diaphragm		present in the gas		EZH	---	Close
				pressure
	Pilot Upper	Pilot cannot feed	Debris or aromatics	Decrease	EZHSO	Open	---
				motorization
	Diaphragm	the regulator	present in the gas		EZH	---	Close
				pressure
		Not proper		Balancing of	EZHSO	Open	---
				pressures and charge
	Regulator	performance of	Debris or aromatics
				or discharge of
	Diaphragm	the motorization	present in the gas
				the motorization
		pressure chamber			EZH	---	Close
				pressure chamber
				Type SA/2 loading	EZHSO	---	Close
				upper casing of
	Pilot	Frozen Pilot,	Moisture in the gas,	regulator, Pilot
		Type SA/2 working	high pressure drop	not supplying
				loading pressure	EZH	---	Close
				to lower casing

R96B

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4

Types EZH and EZHSO

Connections

Inlet/Outlet : CL150 RF - CL300 RF - CL600 RF

PN 16B - PN 25B - PN 40B

Other configurations available

(contact factory)

Pilot feed:	1/4’’ NPT female
Pilot Reject:	1/4’’ NPT female
Pilot impulse:	1/4’’ NPT female
Slam-shut impulse:	1/4’’ NPT female
BM* vent:	1/4’’ NPT female
Impulse tube diameter:	Interior Ø 8/10 mm
Contact switch:	See NTAOS2
* BM - Mechanism Box

Material

Body:	Steel
Connecting parts and bottom:	Steel
Actuator:	Steel
Regulator/Slam-shut orifice:	Stainless steel
Regulator valve plug:	Stainless steel
Slam-shut valve plug:	Stainless steel
Regulator plug disc/
Slam-shut O-rings:	Nitrile (NBR) or
	Fluorocarbon (FKM)

LABELLING

BMS Setting

Security Class

A

B

Max only

BMS 027/017

BMS 162

BMS 236/315

BMS 071

Min only

All

OS2

-

Max-Min

types of BMS

Standard

EN 14382

-

EZH

EZHSO

Failure mode

FC

FO

DN 25	50 80 100
CL150 RF	CL300 RF	CL600 RF
PN16B	PN25B	PN40B

Other configurations available (contact factory)

REGULATEUR/REGULATOR

norme

EN 334

mode défaillance

DN

PN

FISHER

standard

failure mode

SECURITE/SLAM SHUT

norme

classe sécurité

Pumax

bar

FRANCEL

standard

slam shut class

1 (Gaz Naturel)Cat IV PS

2

28320 Gallardon-France

GROUPE

bar

PT

bar

Temp TS

-20/+60°C

Class

Type

Cg

0062

série

Date Fab/Test

DD MM YEAR

matériau

A352LCC+A350LF2

N°serial

Mfg/Test date

shell

Reduction

0

1

2

3

Cg

See Table 3

IS

Depending on BMS

DS

configuration

		CLASS				PN
	150		300	600	16B	25B	40B
Pumax	18.9		50	100	16	25	40
PT	32		79	158	26	40	63
PS	18.9		50	100	16	25	40

Figure 3. Types EZH OS2 and EZHSO OS2 Label (X Body)

Europe, Middle East, and Africa Document Only

Failure mode FC FO

DN 25 50 80 100

REGULATEUR/

REGULATOR

DN

PN

mode défaillance failure mode

N° sérieserial

CL150 RF	CL300 RF	CL600 RF
PN16B	PN25B	PN40B

Other configurations available (contact factory)

EZH EZHSO

norme

Reduction

0

1

2

3

EN 334

Cg

See table 3

standard

Type

IS

Cg

Date

DD MM YEAR

Date Fab/Test

Mfg/Test date

PS					bar	PT		bar	Pumax		bar
															CLASS			PN
		Temp TS						Class 2						150	300	600	16B	25B	40B
					-20/+60°C
		matériau											Pumax	18.9	50	100	16	25	40
		shell				A352LCC+A350LF2					0062		PT	32	79	158	26	40	63
(Gaz Naturel)					FISHER
GROUPE		1 Cat	IV					FRANCEL					PS	18.9	50	100	16	25	40
								28320 Gallardon-France

R97

Figure 4. Types EZH and EZHSO Label (E Body)

5

Types EZH and EZHSO

DIMENSIONS AND WEIGHTS
		DN 25, 50, and 80					DN 100
				E		E	I	H
			Indicator cover	J	K	Indicator cover
I	H	K				removal clearance
			removal clearance
		C			C

B	A

D	B	D
	A
G
	G

F	25 mm
	Mechanism box		25 mm
	removal clearance	F
			Mechanism box
			removal clearance
			R112a

Figure 5. Dimensions — Types EZH OS2 and EZHSO OS2

(Horizontal Position)

DN 25, 50, 80, and 100

E	I	H	Table 5. Approximate Regulator Weights
	J		Types EZH OS2 and EZHSO OS2
		DN		WEIGHTS (kg)
			CL150/PN 16B	CL300/PN 25B/PN 40B	CL600
		25	49	50	51
C		50	81	83	85
		80	168	175	177
		100	237	250	265
		For Type EZHSO OS2 version add 1 kg			R113a

	B			A					Table 6a. Dimensions — Types EZH OS2 and EZHSO OS2
					D
												OVERALL DIMENSIONS (mm)
	G								DN			F				G
										Diaphragm		Piston	Bellows		Diaphragm	Piston	Bellows
		F			25 mm				25
					Mechanism box				50
					removal clearance						181	204		223	162	71	74
Figure 6. Dimensions — Types EZH OS2 and EZHSO OS2									80
									100
			(Vertical Position)
					Table 6b. Dimensions — Types EZH OS2 and EZHSO OS2
							MAXIMUM OVERALL DIMENSIONS (mm)
DN				A			C					H			J
						B			D	E				I			K
	CL150 CL300 CL600 PN 16B PN 25B PN 40B						Type PRX	Type PRX			Type PRX Type PRX				Type PRX	Type PRX
							Horizontal	Vertical			Horizontal Vertical				Horizontal	Vertical
25	184	197	210		193.5	250	290	310	315	320	260	250		113	280	190	38
50	254	267	286	254	267	265	320	320	330	380	310	310		144	270	190
80	298	317	337	310	317	301	400	400	366	500	390	390		200	270	270	51
100	352	368	394	350	368	345	442	427	410	580	394	394		240		140

R114a

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Types EZH and EZHSO

DN 25, 50, and 80

DN 100(1)

		E				E	I	H
	Indicator cover				K	Indicator cover
		J	I	H		removal clearance
K
	removal clearance
C					C
B					B
		A				A		R115a

Figure 7. Dimensions — Types EZH and EZHSO

(Horizontal Position)

	DN 25, 50, 80, and 100		Table 7. Approximate Regulator Weights
			Types EZH and EZHSO(1)
E	I	H
		DN		WEIGHTS (kg)
	J		CL150/PN 16B	CL300/PN 25B/PN 40B	CL600
		25	38	39	40
		50	71	74	75
		80	145	151	153
C		100	211	224	239
		(1) For Type EZHSO version add 1 kg
					R116a

B

A

Figure 8. Dimensions — Types EZH and EZHSO

(Vertical Position)

Table 8. Dimensions — Types EZH and EZHSO

							MAXIMUM OVERALL DIMENSIONS (mm)
DN				A				C				H				J
							B				E				I				K
	CL150	CL300	CL600	PN 16B	PN 25B	PN 40B		Type PRX		Type PRX		Type PRX		Type PRX		Type PRX		Type PRX
								Horizontal		Vertical		Horizontal		Vertical		Horizontal		Vertical
25	184	197	210		193.5		62	290		310	320	260		250	113	280		190	38
50	254	267	286	254	267		83	320		320	380	310		310	144	270		190
80	298	317	337	310	317		105	400		400	500	390		390	200	270		270	51
100	352	368	394	350	368		137	442		427	580	394		394	240			140

R117a

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Types EZH and EZHSO

	TYPE
FILTER	SA/2
	V

R

M

UPPER

DIAPHRAGM

TYPE
PRX/120	PILOT DISK

S

B

L

A

LOWER REGULATOR DIAPHRAGM DIAPHRAGM

TYPE EZH

Inlet pressure (Pu)

Motorization pressure (Pm)

TYPE PRX:

Pilot feeding pressure (Pup)

S - BLEED PORT

TYPE SA/2

Outlet pressure (Pd)

B - SUPPLY PORT

V - SENSING

L - MOTORIZATION PORT

R - PILOT

R98

Atmospheric pressure (Pb)

A - SENSING PORT

M - INLET

Figure 9. Type EZH DN 25/50/80 (Spring-to-Close Version) Operational Schematic

DESCRIPTION

The Types EZH and EZHSO regulators consist of:

•Version without Integral Slam-Shut Valve:

-An "E Body" or an "X Body plus a cap"

-A compensation valve, an interchangeable orifice

-An actuator with position indicator

-A pilot system adapted to the required pressure setpoint

•Version with Integral Slam-Shut Valve:

-Same parts and sub-assemblies as in the version without slam shut

-An "X Body"

-A valve with tight shut-off O-ring

-An automatic slam-shut bypass

-A release relay Type OS2 (see instruction manual NTAOS2) consisting of:

·A mechanism box (BM)

·A safety manometric box (BMS) connected to the outlet side of the regulator

PRINCIPLE OF OPERATION

Type EZH — Spring-to-Close Version

Type EZH Single-Pilot Regulator

(Figures 9 and 10)

The pilot-operated Type EZH uses inlet pressure as the operating medium, which is reduced through pilot operation to load the actuator diaphragm. Outlet pressure (Pd) opposes the motorization pressure (Pm) in the actuator and also opposes the pilot control spring.

When the outlet pressure (Pd) drops below the setting of the pilot control spring, pilot control spring force on the pilot diaphragm thus opens the pilot valve plug, providing additional motorization pressure (Pm) to the actuator diaphragm. This diaphragm motorization pressure opens the main valve plug, supplying the required flow to the downstream system.

Any excess motorization pressure on the actuator diaphragm escapes downstream through the bleed restriction in

the pilot.

Europe, Middle East, and Africa Document Only

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Types EZH and EZHSO

V

R

S

M	B
	L
	A

R2

RP

IP

IS

	Inlet pressure (Pu)
	Motorization pressure (Pm)	TYPE PRX:
	Pilot feeding pressure (Pup)	S - BLEED PORT	TYPE SA/2
	Outlet pressure (Pd)	B - SUPPLY PORT	V - SENSING
		L - MOTORIZATION PORT	R - PILOT
	Atmospheric pressure (Pb)
		A - SENSING PORT	M - INLET

Figure 10. Type EZH-OS2 DN 100 (Spring-to-Close Version) Operational Schematic

When the gas demand in the downstream system has been satisfied, the outlet pressure (Pd) increases. The increased pressure is transmitted through the downstream control line and acts on the pilot diaphragm. This pressure exceeds the pilot spring setting and moves the Type PRX diaphragm, closing the Type PRX orifice and interrupting the motorization pressure supply to main valve actuator.

The excess of motorization pressure (Pm) acting on both the main diaphragm and Type PRX pilot bleeds to the downstream system through a bleed restriction in the pilot.

For Type EZH DN 100 a check valve (Figure 26) is installed between outlet pressure and motorization pressure impulse lines; this valve will protect the diaphragm assembly from wrong procedures during startup, avoiding a too high pressure differential between outlet and motorization pressure.

Type EZHSO — Spring-to-Open Version

Type EZHSO Single-Pilot Regulator

(Figures 11 and 12)

CAUTION

The pilot-operated Type EZHSO (Spring-to- Open version) will fail in open position in case of main valve diaphragm failure or lack of pressure supply to the pilot (see Table 4 for Failure Mode Analysis).

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Types EZH and EZHSO

UPPER DIAPHRAGM

TYPE	PILOT DISK
PRX/120

FILTER		TYPE
	V	SA/2

R

M

REGULATOR

DIAPHRAGM

S

B

	L
	A	R3
	LOWER DIAPHRAGM
R2		R4

TYPE EZHSO

	Inlet pressure (Pu)
	Motorization pressure (Pm)	TYPE PRX:
	Pilot feeding pressure (Pup)	S - BLEED PORT	TYPE SA/2
	Outlet pressure (Pd)	B - SUPPLY PORT	V - SENSING
		L - MOTORIZATION PORT	R - PILOT
	Atmospheric pressure (Pb)
		A - SENSING PORT	M - INLET

Figure 11. Type EZHSO DN 25/50/80 (Spring-to-Open Version) Operational Schematic

Type EZHSO uses inlet pressure as the operating medium, which is reduced through pilot operation to load the actuator diaphragm (lower chamber). The upper case of

Type EZHSO actuator is filled with pressure coming from pre-regulator Type SA/2, which reduces inlet pressure (Pu) to the constant value of outlet pressure plus approximately 3 bar. This pressure opposes the main spring force

that tends to open the regulator. Outlet or downstream pressure (Pd) opposes the pilot control spring. When outlet pressure drops below the setting of the pilot control spring, pilot control spring force on the pilot diaphragm opens the pilot valve plug, providing additional motorization pressure (Pm) to the actuator diaphragm.

This diaphragm motorization pressure opens the main valve plug, supplying the required flow to the downstream system.

Any excess motorization pressure on the actuator diaphragm escapes downstream through the bleed restriction in the pilot.

When outlet pressure increases over the setting of the pilot spring, the pilot valve plug will be closed reducing motorization pressure to the actuator diaphragm; the pressure in the upper case will force the regulator to close.

For Type EZHSO DN 100 a check valve (Figure 26) is installed between outlet pressure and loading pressure

impulse lines; this valve will protect the diaphragm assembly from wrong procedures during startup, avoiding a too high pressure differential between outlet and motorization pressure.

EZH and EZHSO Series Adjustment

The adjustment of the regulator is performed by means of the pilot adjusting screw, which causes variation of the compression of the control spring.

Adjustment is performed while the regulator is in operation with the aid of a pressure gauge to monitor downstream pressure.

The shut-off valve downstream of the regulator must not be completely closed, it is necessary that a small quantity of gas flows downstream to allow the outlet side to vent when it is necessary to lower the pressure.

Loosen the Type PRX pilot locknut and turn the adjusting screw slowly clockwise to increase outlet pressure and counterclockwise to decrease outlet pressure. Use a pressure gauge to monitor the outlet pressure until the desired pressure is reached. No adjustment is needed to the Type SA/2 stabilizer filter.

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Types EZH and EZHSO

V
R
	S
M	B
	L
	A
	R3
		R4
R2
	RP	IP

	Inlet pressure (Pu)
	Motorization pressure (Pm)	TYPE PRX:
	Pilot feeding pressure (Pup)	S - BLEED PORT	TYPE SA/2
	Outlet pressure (Pd)	B - SUPPLY PORT	V - SENSING
		L - MOTORIZATION PORT	R - PILOT
	Atmospheric pressure (Pb)
		A - SENSING PORT	M - INLET

Figure 12. Type EZHSO DN 100 (Spring-to-Open Version) Operational Schematic

MONITORING SYSTEMS

Monitoring regulation is overpressure protection by containment, therefore, there is no relief valve to vent to the atmosphere. When the working regulator fails to control the pressure, a monitor regulator installed in series, which has been sensing the downstream and control pressure, goes into operation to maintain the downstream pressure at a slightly higher level than normal pressure. During an overpressure situation, the monitoring system keeps the customer on line.

Also testing is relatively easy and safe. To perform a periodic test on a monitoring regulator, increase the outlet set pressure of the working regulator and watch the outlet pressure to determine if the monitoring regulator takes over at the appropriate outlet pressure.

Wide-Open Monitoring Systems

In normal operation of a wide-open configuration, the working regulator controls the system’s outlet pressure. With a higher outlet pressure setting, the monitor regulator senses a pressure lower than its setpoint and tries to increase outlet pressure by going wide open. If the working regulator fails, the monitoring regulator assumes control and holds the outlet pressure at its outlet pressure setting.

Figure 13 shows an upstream wide-open monitor TypeEZH

(Spring-to-Close) and a downstream active regulator

Type EZHSO (Spring-to-Open). With this configuration, in case of regulator main diaphragm failure, it will fail in open position letting the monitor work properly; in case of monitor main diaphragm failure, it will fail in close

position guaranteeing a protection against overpressure to downstream system.

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